An air-conditioning system of an aircraft is designed to provide a constant flow of fresh air into a pressurized body of the aircraft for ventilating one or more cabins of the aircraft and/or to maintain a relatively constant and comfortable temperature and humidity level of the ventilation air for the passengers and crew in the aircraft, both on the ground and in the air. Typically, the air-conditioning system includes at least two substantially symmetrical and independent air-conditioning units referred to as air-conditioning packs, e.g., left air-conditioning pack and right air-conditioning pack, that are disposed in an unpressurized area of the aircraft. The air-conditioning packs are configured to receive engine bleed air, process the engine bleed air, and generate conditioned air for air-conditioning and pressurization of the one or more cabins of the aircraft.
The air-conditioning packs are generally known to have low inherent reliability because they are a high vibration and high heat system which results in frequent performance degradation and/or failure of the air-conditioning pack components. Such performance degradation or failure of the air-conditioning packs may result in high operational and maintenance cost to the aircraft operator. For example, if one or both the air-conditioning packs fail during flight, the aircraft may be restricted to fly at a lower altitude than the aircraft's typical cruise altitude. Flying at a lower altitude results in significantly higher fuel burn, which in turn translates to high operations costs and monetary losses for the aircraft operator. Furthermore, the failure or even a degradation in performance of the air-conditioning packs that control the temperature inside the passenger cabins would result in passenger discomfort. Also, in some cases, the failure or degradation in performance of the air-conditioning packs may result in maintenance delays, cancellation of flights, and/or flight exceptions, resulting in huge monetary losses for the aircraft operator. Therefore, the a health of the air-conditioning packs of the aircraft is vital to an efficient operation of the aircraft as well as to ensure passenger comfort.
Conventional systems for monitoring the health of air-conditioning packs (air-conditioning health monitoring system) in aircraft, such as Boeing 737, McDonnell Douglas MD-88, etc., are limited to one or two sensors that monitor the temperature of the conditioned air at the output of the air-conditioning packs. The conventional systems may generate an alert when the temperature of the conditioned air is above or below a threshold temperature value or when at least one of the air-conditioning packs fail. However, said alerts do not identify the discrepant component of the air-conditioning packs that is causing of the performance degradation or failure of the air-conditioning packs. Further, it may be difficult for the maintenance crew to reproduce a performance degradation or failure of the air-conditioning packs that occurred while the aircraft was in flight since the exact variables of flight are not present while the aircraft is on the ground for maintenance. Therefore, the maintenance crew often has to conduct extensive troubleshooting to determine which component of the air-conditioning packs has failed or is functioning incorrectly, replace said component, and/or send the failed component for repair. An error in the troubleshooting may result in the wrong component being replaced and the maintenance crew may have to spend additional time finding the discrepant component, thereby increasing the maintenance time. Additionally, when the wrong component is replaced and sent to the repair shop, the component has to be tested and recertified before installing it back on the aircraft resulting in additional maintenance cost and time.
Additional sensors can be installed in the air-conditioning packs to provide detailed information regarding the performance of the different components of the air-conditioning packs, thereby improving the ability of the maintenance crew to rightly identify and troubleshoot a discrepancy in the air-conditioning packs in a first attempt. However, electrical and hardware limitations of aircraft, such as Boeing 737, McDonnell Douglas MD-88, etc., restrict the number of additional sensors that can be installed in the aircraft for monitoring the health of the air-conditioning system. For example, a flight data acquisition unit of the aircraft that is a central collection point for the sensor inputs has less than ten sensor input ports available for system monitoring purposes, thereby limiting the number of additional sensors that can be installed for air-conditioning health monitoring. In other words, the configurable data receiver unit may have limited bandwidth for additional sensors. Further, the conventional air-conditioning health monitoring systems follow a reactive approach where alerts are generated after the components of the air-conditioning packs have failed.
Newer aircraft, such as Boeing 777, Boeing 787, etc., do have a more predictive air-conditioning health monitoring system. However, said systems on the newer aircraft are invasive, that is, they require significant structural modifications to the aircraft ducting and/or equipment, such as drilling holes. Such modifications would increase the chances of fatigue failures, cracking, etc., which translates to additional operational and/or maintenance costs to the aircraft operator. Further, the features of the predictive air-conditioning health monitoring system in the newer aircraft are not available in the base model of the aircraft. Instead, they are provided as add-on features in higher models or as accessories that can be purchased at a higher premium.
In view of the above mentioned shortcomings of existing air-conditioning health monitoring systems, there exists a need for an improved air-conditioning health monitoring system that is also cost-efficient.